v0.9.1 Phase 3: Workflow gates and handoffs between Fleet roles

[Hmbown]

Parent: #4175

Problem

Multi-step workflows need explicit handoffs between Fleet roles (scout → implementer → reviewer → verifier → release_lead) with block/approve semantics. Today #4013 describes post-agent verification hooks but not role-to-role workflow gates.

Scope

Phase 3: gate nodes and handoff artifacts in Workflow, executed by Runtime after Fleet-resolved agents complete.

Canonical stopship / release pipeline roles

Role	Gate behavior
scout	Read-only; produces structured findings artifact
implementer	Writes code; blocked until scout artifact approved or skipped
reviewer	Reviews diff; block or approve implementer output
verifier	Runs compile/test/lint gates (#4013); block on fail
release_lead	Final checklist; approves lane completion

Gate semantics

• block — downstream role cannot start until gate passes or human approves override
• approve — explicit promotion of artifact to next role's context substrate
• escalate — after N retries, surface to parent / codewhale lane status

Handoff artifacts are lane-scoped (stored under lane id), not Fleet-scoped.

Relationship to #4013

#4013's compile/test/lint/review hooks become verifier role gates inside Workflow — not ad hoc post-hooks owned by Fleet.

Non-goals

• Replacing human code review for production releases
• Fleet owning gate configuration (gates live in Workflow definition; Fleet only supplies roles)

Acceptance criteria

• Workflow supports gate nodes: on: role_complete, gate: verify|review|approve, on_fail: retry|block|escalate.
• scout → implementer handoff passes findings artifact id into implementer context.
• reviewer block prevents verifier/implementer retry until resolved.
• verifier runs configurable compile/test/lint suite; failures retry implementer with gate output.
• Lane status shows current gate state and blocked reason.
• Tests cover block/approve/retry/escalate paths.

Related

• v0.9.1 architecture: Fleet / Workflow / Lane / Runtime product model (canonical tracker) #4175 — Product model tracker
• v0.9.0 Phase 1: Lane CLI + Runtime backends (tmux, worktrees, stream-json logs) #4176 — Lane CLI + Runtime (Phase 1)
• v0.9.1 Phase 2: Workflow steps reference Fleet roles (not raw prompts/profiles) #4177 — Workflow role resolution (Phase 2)
• v0.9.1: Stopship workflow as fleet-backed lane (dogfood #4090/#4093/#4094) #4178 — Stopship dogfood lane
• v0.9.4 WhaleFlow: verification gates (compile, test, lint, review as post-agent hooks) #4013 — Verification gates (implement as verifier role, not Fleet hook)
• v0.9.0 Workflow: product-readiness tracker #4038 — Workflow product-readiness
• v0.9.0 remaining: Workflow automatic launch and unified activity UI #4110 — WorkflowPanel shows gate/block state
• v0.9.0 execution board: lane order, dependencies, and agent protocol (canonical packet) #4092 — Triage / execution order